I read Larry's post as meaning that from the civil courts we might eventually lead into a criminal court or congressional action. I guess I'm naive. I didn't see anything suggesting illegal activity in what he said.
That said, the real thing I want to respond with here is that the federal government has no authority to use drones to kill any targeted individual anywhere in the world - not in the US and not outside of the US.
The United States Constitution defined, created, and empowered the US government. Outside of power granted in the Constitution the US government does not exist. When individuals or agencies that happen to be part of government behave outside of the Constitution then they are acting as rogues and need to be criminally prosecuted. Onshore or offshore, the Constitution enables and limits the US government. Natural born citizen or illegal immigrant, the Constitution enables and limits the US Government. There are no exceptions based on a person's birth place or location in the world. All dealings by the government, no matter with whom or about what, must be within the confines of authority granted in the Constitution.